This study aims at assessing the effects of an early occupational therapy intervention on the cognitive development and the development of attachment patterns in ELBW infants. The intervention, given weekly at home from six months to 12 months, aimed at supporting parent-child interaction and enhancing motor control and coordination. The study population consisted of 100 ELBW infants matched in pairs in accordance to their pre-perinatal risk scores and allocated successively to intervention or non-intervention groups. Cognitive development was assessed with the Bayley Scales at age two and with the WPPSI at age four. Attachment to primary caregiver was assessed with the Preschool Assessment of Attachment (PAA). Cognitive performance was within age norms in both groups at both ages. Intervention did not show any effect on cognitive performance at the age of two years. At the age of four years, cognitive level was overall, and most notably for verbal performance, higher in the intervention group than in the control group. There was an over-representation of the so-called atypical attachment patterns (those not fitting the normative A, B, or C categories) in the control group. The results are discussed in terms of finding more global ways to support the development of at risk pre-term children.